Roll stands for rolling mills

ABSTRACT

A roll stand for rolling mills utilizes roll frames having frame caps held down by means of pre-stressed tie rods. In one construction four tie rods in all are used and receive at their upper ends a stationary top plate seating against pre-stressing units at the upper ends of the tie rods. The top plate bears against screw-threaded sleeves seating against column embers of the frame. A support frame for the frame caps seats against ring nuts rotatable in screw-threaded sleeves for screwdown adjustment, and hydraulic cylinder piston units are provided between the top plate and the frame cap support frame to maintain pressure between the ring nuts and the sleeves or to release said pressure during screwdown which is effected by rotating the ring nuts from a common drive.

United States Patent [191 Gross 1 Feb. 20, 1973 [54} ROLL STANDS FOR ROLLING MILLS [76] Inventor: Erich Wilhelm Gross, Scheidt-Saar, Primary Larson Germany Attorney-John J. Dennemeyer [22] Filed: NOV. 19, 1970 57 ABSTRACT [21] Appl' 91,055 A roll stand for rolling mills utilizes roll frames having frame caps held down by means of pre-stressed tie [30] Foreign Application Priority Data rods. in one construction four tie rods in all are used Nov 22 l 969 German P '9 58 70 0 and receive at their upper ends a stationary top plate y seating against pre-stressing units at the upper ends of [52] U 8 Cl 72/248 the tie rods. The top plate bears against screw- [51] 1.31/04 ahaaaaaa aaaaaa aaaaaaa aalaaaa aaaaaaa af aha [58] Field of Search ..72/237, 241,243,245,24s frame- A PP frame the frame caps Seats against ring nuts rotatable in screw-threaded sleeves 5 References it for screwdown adjustment, and hydraulic cylinder piston units are provided between the top plate and UNITED STATES PATENTS the frame cap support frame to maintain pressure 3,580,035 5/1971 Bond etal. .12/243 betwefln the ring nuts and the sleeves or to release 3,526,118 9/1970 said pressure during screwdown which is effected by 3,587,278 6/1971 rotating the ring nuts from a common drive. 3,286,501 11/1966 693,031 2/1902 Kennedy ..72/248 4 Claims, 4 Drawing Figures PATENTED FEBZ 01975 SHEET 10F 2 PAIENIED FEBZOIEIB 7 3 717, 021

SHEET 2 [IF 2 ROLL STANDS FOR ROLLING MILLS The invention relates to roll stands for rolling mills in which the stands have frame caps displaceable vertically for screwdown adjustment along pre-stressed tie rods by means of rotatable ring nuts rotatable on four stressed, non-rotatable screw-threaded sleeves and in which the upper roll follows the screwdown movement.

The previous construction of such a screwdown device embodies two nuts for each tie rod which receive between them the frame cap or, in the case of frameless stands, the chocks of the upper roll. Both nuts must be positively driven in the same direction in order to adjust the frame cap with the upper roll. Since the ring nuts are subjected to the pre-stressing of the tie rods the pre-stressing must be reduced preliminarily for each screw-down operation, for which purpose hydraulically extensible tie rods have been developed as described in German specification No. 1,287,543.

For smaller roll stands for rod mills which only have to be adjusted for a change in programme or between the passes during entry into the train, the reduction in the pre-stress does not involve problems and has further the great advantage that the roll pressure can be rapidly reduced on jamming of the rolls by lengthening the tie rods to such an extent that remaining rods between the rolls can travel onwards. For reversing rolling mills however the tie rods are more heavily stressed as regards their fatigue strength if they must be screwed down after each pass and released before the screwdown operation.

It is further known with frameless roll stands to replace the lower ring nuts by hydraulic pressure devices surrounding the tie rods which press the upper chocks together with the roll constantly against the upper vertically adjustable compression nuts. During the screwdown the hydraulic stress pressure is reduced in order to enable the upper compression nuts to be rotated more easily, as described in German specification No. 1,281,378. The ring-shaped hydraulic pressure units however require dismounting of the upper chocks if the sealing devices are damaged. This factor becomes serious in the case of heavy stands.

The invention is directed to the problem of providing a ring nut screwdown device for tie rod stands which has a substantially true pre-stressing condition without the pre-stressing of the tie rods needing to be eliminated for each screwdown operation. Hydraulic units for assisting the screwdown operation should moreover be readily accessible without the need to disassemble the stand.

The present invention provides a construction in which the four tie rods are connected together at their upper ends by a stationary top plate resting on the threaded sleeves of the screwdown device and subjected to the prestressing in the tie rod, adjuster cylinders being fitted to the top plate, which cylindersengage the frame cap and press it against vertically adjustable ring nuts associated with the several tie rods respectively.

With the upper stationary top plate and the adjustable frame caps the stand has a construction similar to a press and the frame caps or a unitary adjuster frame is free from the pre-stressing forces and hence the prestressing does not have to be overcome when these caps are displaced forscrewing down the upper roll of the stand. The hydraulic adjuster cylinders which control the screw-down movements of the frame cap in cooperation with the rotatably driven ring nuts are arranged similarly to the return-stroke cylinder of a press, that is to say, they are external and therefore readily accessible. By the fact that the four tie rods are connected at their upper ends by the top plate a stiff tie rod frame is provided whereby in essentials the guiding of the adjustable frame caps is obtained by only four ring nuts in place of four pairs of ring nuts, as previously.

As a result of the placing of the adjuster cylinder externally of the frame caps the space above the upper end faces of the frame columns is not needed either for a second ring nut, as in German specification No. 1,287,543, or for a pressure unit of the ring-piston type as in German specification No. 1,281,378, and thus the invention provides a way of guiding the frame caps additionally at extended ends of the frame columns apart from being guided on the threads between the ring nuts and the threaded sleeves. These upper ends are of cylindrical form according to a further development of the invention and arranged as guides for the frame caps or for a frame cap support frame. The cylindrical guide ends of the frame columns can be provided with a flattened part in the lower region in line with the wear strips defining the window openings, the wear strips being extended along the flattened part for guiding the upper chocks.

The hydraulic adjustment forces exerted by the adjuster cylinders should be as great as possible during rolling, and in any case greater than what is required for balancing the weight of the frame caps together with the upper roll or the upper roll set in order that the oil film between the screw threads of the screwdown device is forced out and the yield under pressure can be held as small as possible. Since the pressure in the adjuster cylinders is variable between this maximum value and a minimum value during the screwdown, the forces for rotating the ring nuts can be small as is known in the case of the tie rod stand already referred to with pressure units of the ring piston type.

One constructional example of a screwdown device according to the invention is shown in the drawings, as applied to a four-high roll stand in which:

FIG. 1 shows the stand in half-section through the plane of a tie rod and in half-side view,

FIG. 2 shows the stand in half-front view and in halfsection through the roll plane,

FIG. 3 is a section on the line IIIIII in FIG. 1, and

FIG. 4 is a section on the line IV-IV in FIG. 1.

The frame construction is in several parts for ready construction and transport. There is shown a lower base frame 12 resting on the base plate 10, separate frame columns 14 resting thereon, a stiff frame cap support frame 16 connecting both frame caps and a stationary top plate 18, and all these parts, with the exception of the frame cap support frame 16, are clamped together firmly by the tie rods 20 but with the interposition of four threaded sleeves 22 surrounding the tie rods. The pre-stressing is effected by four ring-shaped hydraulic pressure units 19 arranged beneath top compression nuts 21 of the tie rods 20 and is constantly maintained. The pre-stressing can naturally also be produced by a so-called hydraulic nut in which the hydraulic pressure can be released after screwing down the compression nuts 21.

The four-high stand shown further embodies two backing rolls 23, 24 with the chocks 25, 26 and two work rolls 27, 28 with their two chocks 29, 30. Hydraulic pressure devices or gauges 32 are provided beneath the chocks 26 of the lower backing rolls 24 for automatic roll gap regulation. Roll bending cylinders 34 act on the extended spindles 23a and 24a of the two backing rolls, which are secured to out-riders 16a of the frame cap support frame 16 on the one hand and out-riders 12a on the base frame 12 on the other hand and serve for crown control of the backing rolls. These features are not essential to the present invention and are referred to only to provide disclosure of an operative structure.

The invention relates to the construction of the screwdown device for the common frame cap support frame 16 together with the upper roll set 23, 27 supported therefrom. For this purpose a rotatably driven ring nut 36 is screwed on the non-rotatable threaded sleeve 22 already referred to, which is subjected to the pre-stressing. Four adjuster cylinders 38 are secured to the top plate 18, the piston rods 39 of which engage the frame 16 at 40 and force the frame constantly against the ring surfaces 36a of the ring nuts 36 which also receive the rolling pressure and transfer it through the threaded sleeves 22 and the top plate 18 to the tie rods 20. The ring nuts 36 serve in part as stop nuts for the frame 16 and determine the vertical position of the upper roll set 23, 27 by the action of the adjuster or balancing cylinders 38.

The ring nuts 36 are rotated by external toothed rings 36b which engage intermediate gear wheels 42 supported in the frame cap support frame 16. The intermediate gear wheels 42 driving the ring nuts 36 engage a central pinion 44 on each side of the stand which, as will be seen best from FIG. 2, are driven by a shaft 46 extending downwardly from the top plate 18. This shaft 46 must be operative during the screwdown movements of the frame 16 and is therefore in the form of a multiple splined shaft. The two driving shafts 46 on each side of the stand are rotatably connected to but axially displaceable by the splines thereof within a worm wheel mounted in a gear box 48 arranged in the top plate 18. Four mutually coupled motors 50 serve for driving the worm shaft 52 the outline only of which is shown in FIG. 1.

During rolling the adjuster cylinders 38 receive a maximum pressure in order to force out the oil film in the screw threads between the ring nuts 36 and the threaded sleeves 22. For screwing down the top rolls 23, 27 between passes for reversing operation of the stand or for coarse adjustment of the roll gap, the stand pre-stressing action produced by the pressure units 19 does not need to be eliminated and it is only necessary to change the pressure in the adjuster cylinders 38 to a minimum value just sufficient to keep the frame cap support frame pressed against the ring surfaces 36a of the ring nuts 36. FIG. 1 shows the frame 16 at the lefthand sectioned portion in the lowest position and the right-hand portion in elevation in the highest position.

It will be seen that with the screwdown device according to the invention the stationary top plate 8 is arranged as a carrier for the easily releasable and accessable adjuster cylinders 38. The top parts of the stand generally do not have to be dismounted for servicing the sealing elements of the hydraulic adjuster means. The top plate 18 further provides a fixed relation for the tie rods one to the other and the frame cap support frame 16 or the two frame caps can be controlled by one ring nut only for each tie rod.

A further advantage of the invention consists in the fact that the motors and gears for the rotary drive of the ring nuts 36 do not now have to be arranged on the frame caps but that the common stationary top plate 18 is available for this purpose and the screwdown members do not therefore have to be raised and lowered by the rotary drive.

With the new construction screwdown can obviously also be effected under roll pressure if the rotary drive for the ring nuts 36 is made correspondingly powerful. The pressure in the adjuster cylinders 38 is then conveniently eliminated completely during the screwdown.

As will be seen from FIG. 1 in conjunction with FIGS. 3 and 4 the upper ends 14a of the frame columns v 14 are made cylindrical and provided with a bushing 17 as a guide for the frame cap support frame 16. In this way the screw threads between the threaded sleeve 22 and the ring nuts 36 are relieved of their guiding function. As will be seen from FIG. 4 the guide ends 14a of the columns 14 are provided in their lower region with a flat 14b to receive the end of an extended wear strip which defines the window openings between the columns 14. The upper chocks 25 thereby secure a better guiding during coarse adjustment of the roll gap.

What I claim is:

1. A rolling mill stand of the type including a pair of roll frames arranged in spaced relationship, a plurality of vertically adjustable rolls, a plurality of vertically adjustable frame caps for supporting said rolls and a plurality of tie rods connected to said frames the improvement which comprises, a stationary top plate, means for connecting the upperends of said tie rods to said top plate, an externally threaded sleeve on each of said tie rods between said top plate and saidframe for receiving the compression force exerted by said tie rods, a vertically adjustable ring nut threadedly engageable with each of said sleeves and a plurality of fluid pressure cylinder and piston units connected to said top plate and said frame caps for releasably urging said frame caps into engagement with said ring nuts.

2. A rolling mill stand in accordance with claim 1 including a plurality of column members on said roll frames, each of said column members being associated with one of said tie rods and having an upper end for supporting said sleeve on a vertical axis and wherein said top plate is supported on the upper ends of said sleeves.

3. A rolling mill stand in accordance with claim 2 wherein the upper end portions of said column members are of circular cross-sectional shape and wherein said frame caps are guidably arranged for vertical movement on said upper end portions of said column members.

4. A rolling mill stand in accordance with claim 3 including chocks for supporting the ends of said rods mounted for vertical movement on each of said roll frames in sliding relationship with an outer surface portion of said column members and wherein said outer surface portion of said column members is provided with a vertically extending flat portion and a wear strip on each of said outer surface portions of said column members. 

1. A rolling mill stand of the type including a pair of roll frames arranged in spaced relationship, a plurality of vertically adjustable rolls, a plurality of vertically adjustable frame caps for supporting said rolls and a plurality of tie rods connected to said frames the improvement which comprises, a stationary top plate, means for connecting the upper ends of said tie rods to said top plate, an externally threaded sleeve on each of said tie rods between said top plate and said frame for receiving the compression force exerted by said tie rods, a vertically adjustable ring nut threadedly engageable with each of said sleeves and a plurality of fluid pressure cylinder and piston units connected to said top plate and said frame caps for releasably urging said frame caps into engagement with said ring nuts.
 1. A rolling mill stand of the type including a pair of roll frames arranged in spaced relationship, a plurality of vertically adjustable rolls, a plurality of vertically adjustable frame caps for supporting said rolls and a plurality of tie rods connected to said frames the improvement which comprises, a stationary top plate, means for connecting the upper ends of said tie rods to said top plate, an externally threaded sleeve on each of said tie rods between said top plate and said frame for receiving the compression force exerted by said tie rods, a vertically adjustable ring nut threadedly engageable with each of said sleeves and a plurality of fluid pressure cylinder and piston units connected to said top plate and said frame caps for releasably urging said frame caps into engagement with said ring nuts.
 2. A rolling mill stand in accordance with claim 1 including a plurality of column members on said roll frames, each of said column members being associated with one of said tie rods and having an upper end for supporting said sleeve on a vertical axis and wherein said top plate is supported on the upper ends of said sleeves.
 3. A rolling mill stand in accordance with claim 2 wherein the upper end portions of said column members are of circular cross-sectional shape and wherein said frame caps are guidably arranged for vertical movement on said upper end portions of said column members. 